Dinâmica do uso e cobertura da terra e fragmentação da paisagem no cerrado piauiense

Abstract

Investigations about the dynamics of land use and land cover changes based on satellite imagery blended with landscape ecology based knowledge allow the establishment of adequate programs towards the conservation of biodiversity as well as the control of the use of natural resources. This work aims to analyze the evolution of land use and cover focusing on metrics gathered from fragmentation of the landscape along the the last 30 years in the cerrado of Piauí-Brazil. The study area still presents large patches of remnants native vegetation of the cerrado biome, but in general the area has been affected by intense deforestation due to the novel agricultural projects. The investigation used the following methodological approach: (1) Mapping landcover using object-based image classification of Landsat 5 and 8 for the years 1986, 1996, 2006 and 2016; (2) Calculation of landscape metrics at the class level for each relief unit by year; (3) Calculation of transitions between landcover classes mapped along the last 30 years in ten-year periods; and (4) Quantification of the conversion increment of vegetation areas for agricultural activities by period and phisiographic relief unit Findings show the effect of the degradation is more pronounced in the relief unit present in the Highlands than in the physiographic units of the studied area. Therefore, it is evident how the terrain the region is determinant for the anthropic occupation, mainly for the mechanic-oriented grain crop. The anthropic activities in this part of the state of Piauí directly affect the vegetation / forest, and this process was intensified every along the time-period studied. Thus, it is possible to affirm that the vegetation of the study area is undergoing a progressive fragmentation process over the years. Metrics show the configuration of fragments changing and becoming more propitious for accentuated edge effects, highlighting the unity of the plateaus, where the matrix of the landscape is in the process of shifting from the Forest / Arboreal Vegetation class to Agriculture.